The present invention relates to a bottle closure having a frusto-conical outer shell and a rib-supported threaded inner shell.
Consumer beverages, such as milk and juices, are commonly packaged in bottles having wide necks. The wide-necked bottles are designed to allow the user to easily dispense a portion of the beverage from the bottle. In recent years, closures having an enlarged top and an inwardly projecting skirt have been used with the wide-necked bottles. The enlarged-top closures allow the consumer to easily pick up the package and open the containers. Further, the enlarged-top closures allow products to be more easily stacked for packing and shipping.
Most enlarged-top closures are injection molded from thermoplastic materials. During the closure manufacturing process, melted material is fed into a multi-part mold where the material is allowed to cool in the shape of the mold. Once the material has cooled, the mold is opened and the closure is released from the mold. If the material is not completely cooled before the mold begins to release the closure, distortions or flaws may form in the closure. Generally, if the molding unit releases the closure by parting, there are few noticeable distortions in the closure. However, if the molding unit must be unscrewed from the closure, such as when the core for producing the threads in the closure is removed, the torque generated by the unscrewing motion can cause any pliable material to twist or turn slightly leaving flaws in the finished closure. On a reverse taper closure, and particularly on a closure having a frusto-conical outer shell with a detailed outer surface, the conventional approach to attempt to overcome the twisting has been to develop means to hold the outer shell as the threaded core is removed. This has not alleviated the problem, however.
Alternatively, the closure may have stripped type threads. However, during production the stripped type threads are forced off the threaded inner core by applying a force to the outer shell of the closure. This force is transferred through the connecting top causing the top to distort or dish. To avoid distortion of the top, the threads can be stripped by applying pressure to the bottom edge of the inner shell. But the stripping element to accomplish this need to fit between the threaded core and the inner shell profile core, generally meaning that the stripping element is relatively thin and fragile. The inner core may also be forced off by applying a force though the center of the inner core. However, this tends to cause distortion or doming of the top and also restricts cooling of the threaded core.
Thus, it would be beneficial to have a double-shelled bottle closure having a frusto-conical outer shell and a threaded inner shell that would not be subject to noticeable distortion as the closure is produced.
The present invention relates to a bottle closure having an outer shell with a frusto-conical configuration and a rib-supported threaded inner shell. The frusto-conical configuration of the outer shell allows the user to easily grip the closure and remove it from a bottle. The inner shell is threaded to engagingly mate with threads of a complementary bottle or similar container. The inner shell is supported by ribs which face toward the outer shell. The ribs provide that the inner shell can be unscrewed from a threaded core of a manufacturing mold during production without causing noticeable distortion in the closure top. Adding support structure, the ribs, to the closure immediately adjacent to the point of resistance (the threads) allows for a shorter cure time and, therefore, a faster production cycle and higher productivity.